#!/bin/bash
num_a=$1
num_b=$2
num_c=$c

if [ -z num_a ];then
echo "please input num_a"
exit
fi

if [ -z num_b ];then
echo "please input num_b"
exit
fi

if [ -z num_c ];then
echo "please input num_c"
exit
fi

echo "the shell name is $0"
echo "the shell params count is $#"
echo "the shell last params is ${!#}"

# $*与$@的区别
for param in "$@"
do 
  echo "this is param => $param"
done

for param in "$*"
do 
  echo "this is param => $param"
done
